Database Systems 6th Edition by Ramez Elmasri, Shamkant B. Navathe

تمرين 10

-A nested query is query within a query. More specifically, a nested query is a parenthesized query that can be used as a value in a number of places, such as instead of a relation or a selection condition. Specify the following queries on the database specified in Figure 3.5 using the concept of nested queries and the relational operators discussed in this chapter. Also show the result of each query as it would apply to the database state of Figure 3.6.
a. List the names of all employees who work in the department that has the employee with the highest salary among all employees.
b. List the names of all employees whose supervisor's supervisor has '888665555' for SSN.
c. List the names of employees who make at least $10,000 more than the employee who is paid the least in the company.